Combination polymerization and alkylation of hydrocarbons



Aug. 1.3, 1940. A. R. GoLDsBY Er Ar. 2,211,747

COMBINATION POLYHERIZATION AND ALKYLATION OF HYDROCARBONS 2 Sheets-Sheet l Filed April 21, 1938 ENToRs roRNEY Aug. 13, l940- A. R. GoLDsBY E1- AL COMBINATION roLYNENIzATIo'N AND ALKYLATION oF HYDRocAnBoNs' yFneapril 21, 193sl -2 sheets-sheet 2 III NEY

V@atente Aug. i3, f

anion.

GMBINATION POLYMERIZATION iiNli AIE, KYLATION 0F HYDROCARBQNS y Arthur iR.. Goldsby, Beacon, and @lande `Watson, Dobbs Ferry, N. Y., assis-nora to 'Elie '.lexas'Company, New York, N. E., la corporation of Delaware Application April 21, 193s, sensi No. stazza' is claims. (ci. 19e-1c) normally gaseous olefins, to higher boiling point oleins which are normally liquid and the alkylay tion of isoparaflinswith these .polymers or the ii) residual unpolymerized oleflns to produce high antlknock motor fuel hydrocarbons. More particularly, the inventionis concerned with the selective polymerization of isomerlc butenes in a cracked C4. fraction of hydrocarbon gases to .pro- 35 .duce di-lsobutylenes and the alkylation of isobun tane with the olefins in the residual Crfraction;

'Moreoven the invention comprises ,important improvements in a method of alkylation, wherein a portion of thezmaterials withdrawn from the re lo laction zone, preferably in the formof an emulsion of theacid and hydrocarbons, is recycled-to the reaction zone ltol improve the' dispersion of the reactants and to increase the'ratio of lsoparafiins' to oleiins' 'in the reaction mixture.

25' Heretofore, in 7the manufacture of iso-octanes from' oleiinic gases containing isobutylene or isomeric butenes, it has been customary to selectively 'plymerlze the isomeric butenes to di-isov butylenes in the presence of a polymerinatiox'r 30 catalyst, and then hydrogenate .the d i-isobutylenes by low pressurehydrogenation using a catalyst,

suchas nickel; or by high pressure hydrogenation using a-catalyst immune to sulfur poisoning, such as.- sulildes of heavy metals, ,particularly suliides" a-of the metalsof the sixth group ofthe periodic system, for example molybdenum, tungsten, nickel or cobalt. In th'e foregoing methods the'hydrogenation operation is expensive and diillcultto control' on account of the catalyst, andrequires a 40 source of hydrogen which is often expensive'. Moreoveig'with some feed stocks and under some vpolyn'ierizirigconditions,there may occur a'substantial depreciation in the antiknock value of the -hydrocarbons as a result of the hydrogenation 43 treatment.v Further, the motor fuelproduced bythis method generally requires -blending with .a light.material, 'such as isopentane, to volatility rangejfor aviation gasoline., f

In accordance with the vpresent inventitni,I in- .ij the di-isobut`y1eneswitn ss'fisobutana in the` presence of talyst. whereby iso'- V tions which indicate merely `the p` cipal prod- En iso-octencs Btylenes Alkylation catalyst Iso-octenes Isobutane This general reaction is disclosed in copending 10' application -of Korpi-Goldsby, Serial iid-150,316, illed June l25, 1937, of which the present invention isv an improvement. The alinrlation stepis of the general type disclosed in copendina application Serial No. 148,978, Korpi-Goldsby, med June 18, l5 1937. This method possessesfurther advantages over the hydrogenation method referred to above, in that it is capable of producing from a Ce cracked hydrocarbon fraction a motor fuel having the required volatility for aviation gasoline with- `20 out blending: also it is capable of handling mirttures of gaseous hydrocarbons including Ca and? .Ci hydrocarbons, while still producing a high j polymerization between the isobutylene and Y, "'butene-i or b utcne-Z,A to form mixed or interpolymers. On account ofthe advantage from the ias yield standpoint, itis preferable to operate so as.

to form as high a 'yield as possible of theA mixed polymer. The formation of the mixed or'finter-` polymer maybe promoted by maintaining a high ratio' of normal butylenes to isobutylene which may be done byrecycling the unreacted normal v butylenes in the polymerization operation.

vThe 'selective polymerization operation may bej carried out in thepresence of suitable catalysts, u

fthe moet common `of` which are phosphoric' ac'id f and dilute sulfuric acid. Both'of these catalysts.

proper conditions, will produce selectively ,cli-isobu'tylerlesl and substantial cross polymerlza-'- tion between the iso and normal butenes.' often y v 'apprx'mcliing` thel theoretical. -The phosphoric 5o catalystis preferably used in the form of a solid lcatalyst comprisinga mixture of phosphoric v acid and-kieselguhr, although liquid phosphoric acid can` be used. 'Rie sulfuric acid catalyst prefarablelis sulfuric' acid offabout to '10%68A strength. At low temperatures this strength of acid will selectively absorb the isobutylene which may then be polymerized by heating the mixture to temperatures of about 200 F. When operating at high temperatures, around 160 to 180 F. using a high ratio of normal butylenes to isobutylene, a cross-polymerization between the isobutylene and normal butylenes may be effected to produce directly iso-octenes.

The hydrocarbons suitable for treatment may be any product containing isobutylene or isomerlc butenes, which may be selectively polymerized. A hydrocarbon fraction containing a mixture of isomeric butenes, for example a cracked gaseous fraction such as still gases containing isobutylene, butene-l and butene-Z, may be used.

' pylene together with other C3 and C4 hydrocarwith the accompanying drawings. Figurel shows of isobutane to oleiins.

bons can be employed.

In accordance with the invention. the charging stock is subjected to a polymerization operation in the presence of a catalyst whereby di-isobutylenes are selectively produced, preferably as a result of a linking together of the iso and normal butylenes. The resulting mixture may be subjected directly to alkylation in the presence of strong sulfuric acid whereby alkylation of isobutane takes place to produce branch chain hydrocarbons, including iso-octanes. In case the isobutane content of the mixture is not suiliciently high, extraneous isobutane may be added. In some cases it may be desirable to separate the diisobutylenes from the unreacted gases and Vsubject thedie-isobutylenes separately to alkylation in the presence of isobutane. The residual gases, from the polymerization reactiongcomprising unreacted butenes and isobutane and normal butane, will usually contain an excess of isobutane and may be subjected to an alkylation operation, with or without further adjustment .of the ratio These residual gases may be further treated to concentrate the isobutane which may be used in thealkyl'ation operation. Moreover, the normally liquid hydrocarbons may be separated from the polymerization products and fractionated to separate any polymers higher boiling than di-isobutylene prior to subjecting the di-isobutylene to'- alkylation. If desired, these higher boiling polymers may beseparately subjected to alkylation in the presence of extraneous isobutane or that contained in the unreacted `gases or both, whereby a splitting of these high boiling olens and alkylation with the isobutane ltakes place to form low boiling products suitable for motor fuel.

The invention will be more fully understoodfrom'the following description read in connection diagrammatically amapparatus for carrying out the process of the invention when the polymerization catalyst is phosphoric acid. Figure 2 shows diagrammaticallyan apparatus'suitable for use when operating with sulfuric acid as the polymerization catalyst.

Referring to Figure 1, a hydrocarbon charging moyal of sulphur and nitrogencompoun'ds, is in'- vtroduced through the line 5 in'which is located a valve 6 and pump 1, into a preheating coil 8 lon cated in a heater I8, which may be supplied with 'd uced throughiine' 41.

and 5: 1, although ratios as high as 20: 1 have been a suitable heating medium. In the preheater the hydrocarbons are heated to a temperature of about 300 to 330 F. and preferably about 320 l?. under a pressure of about 500 to 600 pounds per square inch, and preferably about 550 pounds. The hot products from coil 8 are transferred through the line I2 to the polymerization chambers i and l5. The polymerization chambers are charged witha solid phosphoric acid catalyst, referred to heretofore. The polymerization chambers are connected in series by a line i@ although they may be connected in parallel whereby a single chamber may be used or both chambers used simultaneously or successively.

While two chambers are shown, itis to be underl.

stood that any number may be used. Sometimes it may be advantageous to use one chamber only while the other is being cleaned out or the catalyst revivied. The reaction products are withdrawn Vfrom the bottom of chamber I through the line I8 and any portion of the products may be recycled to either or both of the chambers by suitablelies (not shown).

The products from the polymerization chambers `are passed through the line I8 to a fractiona' fg tor wherein the butanes and butenes may be removed overhead through the vapor line 2| to a condenser coil 22 wherein the vapors are condensed and the liquids conducted through a rundown line 24 to the receiver 25. The di-isobutylenes are collected on a chimney tray 28 and are passed to a stripping column 29 from which they are withdrawn through the line 30 in which is located a valve 3| and pump 32. The bottoms from the fractionator 20, comprising the polymers higher boiling than the di-isobutylenes. are withdrawn from the lower portion of the fractionator through the line 34 and may be discharged from the system through valve controlled line 3E. 'Ihe di-isobutylenes from the stripper 2S may be passed through the lines 30, 38 and 38 containing a suitable cooler (not shown) to the alkylation tank Il, wherein they are contacted `with sulfuric acid introduced through the 'valve controlled 'line M by the pump l This sulfuric acid may be of a suitable alkylation strengthjpreferably between about 92 and 98%, for example 94%. Isobutane may also be introduced'into the system through the valve controlled line' 41 by pump 48. The isobutane-50 l may be substantially pure isobutane or a hydroi pump 5l through a suitable cooler (not shown) to the alkylation tanks as a source of isobutane. any additional isobutane required being intron is preferame to have ruo of manutan@ to olens in the feed subjected to alkylation of at least about 1:1 and preferably between about 3:1

used. The proportion of acid is ordinarily about 1 part by ,weight or more to 1 part of olefin charged. The temperature in the allwlation tanks is preferably maintained at around normal atmospl'ieric temperature, for example 'I5 to 120 F.

- The timeI of reaction in the alkylation tanks may vary from about 20 minutes tb several hours and preferably is about one hour. The alkylation tanksv are connected in series by the line 85, and

lil

the hydrocarbons, in passing therethrough, are n essere? intimately contacted with theacid catalyst by .stirrers il and 55 or any-well known or preferred type of mixing means. While the polymers may be fractionated and d lthe di-isobutylenes used, for example the product .from stripper 29, it may be advantageous to alkylate the polymerization product as such, without debutanization or-fractionation. For such purpose the reaction products from the polyl merization 4chambers I4 and i5 4may be passed through4 the lines Bland 38 directly to the alkylation operation, the valve ll in the line I8 and valve Sli in the line 34 being closed. When using this mixture the isobutane present may be suillcient forthe alkylation operation. Howeverfif desired, additional isobutane may be added through the line 41.

Provision is made forseparately alkylating the bottoms from fractionator. This product may '20 'be withdrawn from the lower portion of the fracvtionator through the line 3 4, valve i2 'in therline and valve 5l 'in the line 51 being closed, and

passed to tankage and then through a cooler and through line 38 to the alkylationchambers. It is 26 to be understood that suitable tankag'e (not shown) is provided for receiving and storing the various fractions from fractlonator 20, so that they may be selectively and separately passed to the alkylation unit. 'Ihese bottoms maybe al' 30- lwlated in the presence` of extraneous isobutane,

jadded through the line 41 or ispbutane from the tank 25 added through the line 5l, or both. It

l Vhas'lcneen foundgthat the isobutane will 4split and alkylate these bottoms to form lower boiling pol-nt' products, such as motor fuel, which are primarily saturated in characten4 Moreover, it

. from the polymerization operation, particularly ,tne product collected in accumulator.. .35, with or ,30 .without further fractionation, may be separately subjected .to alkylation, for example by passing them through the line 50 to the alkylation tanks.

These gases usually containa relatively high ratio ofisobutane to oleflns due to the partial removal of the oleiins in the polymerization operation. 'Wherethe original charging stock was a C4 fraction, the ratio of .isobutane to butenes may, rangev from about 1.5:1 to 3:1 and is4 a good charging 'stock for alkylation. m l The operation in the alkylation tanks 4i, and 42' is preferably in the liquid phase and isordinarily carried out under pressures not greatly in excess of that nedess ary to maintain the liquid phase, such' as125 to 150 pounds, although it may ,be advantageous in some cases to maintain a 2 higher pressure, such as for example substantiallyA that maintained in the polymerization operation. The te'.lky1ation tanks are connected in series by the line B5 and' while two tanks are'shown, any

w number may be used-and 'of sufficient-'size to give fthe desired time of reaction.' The reaction products are transferred f i'oiii the last tank 4 2 through the line il to a .separator 1li.4 By suitable regulation .of the valve 1I 'in the by-pass line 12, a portion or all of this mixture-may be recycledby the pump 13. through the line 14 back to the iirst reaction tank 4l to pass again through the system. This recycling of the acid-hydrocarbon mixture or emulsion is often desirable and by. 'using a highrecycle ratio, the isobu'tane to ole'iinv concentration'of the 'reaction mixture vin the alkylation tanks can be kept relatively high, whereby favorable conditions for the production of a high yield of high antisknock products boiling within' the gasoline range areproduced. For' example, arecycle ratio of v3 to 1Q times; and prefis intended niet the exit 'gases fraction is treated and theexcess C4 hydrocar-- erably about d or d times the original drocaral loon charge may .be advantageous. The mixture in the settler 10 is allowedv to stratify and the acid collecting in the lower portio'nthereof may ide withdrawn through the line 15 which communig cateswith the line 14 whereby the acid is recirammonia or lime, introduced through the line 88 in which is located a pump 8. In the mixer the neutralizing solution and hydrocarbons are intimately mixedv to neutralize vacids in the hydrocarbons. The mixture is' .then transferred .1

` through the valve controlled line 81 to a separator wherein the neutrali-zer and hydrocarbon are allowed to stratify and the neutralizer separating in the lower portion thereof recirculated .to lthe mixer through the valve controlled line I! by pump 8B or any portion or all withdrawn through valved line 83. -The neutralized hydrocarbons are passed from the separator I8 through-.the line l2 by pump 83 to a debutaniner or stabilizer M in ,which materials lighter thanthe desired gasoline, lsuch as normally1 gaseous hydrocarbons lighter than-n-butane, and all or a portion ofthe n-butane, are released from the top of the'debutanlzer through the valve controlled line 95. This gaseous fraction, either without or with fractionation l to concentrate the isobutane, may be recycled to the alkylation unit bysuitable lines (not shown). Bottoms are withdrawn from the lower portion of the debutanizer @t through the line 96 and passed 'to a fractionator 9d. VI it is usually desirable' to debutanize the valkylated product especially when a substantial amountpf vlower boiling normally gaseous ll'iydrocarbonsfis present. Ins-orne cases it maybe unnecessary to debutanize the-prod=f uct, for'A example when only a C4 hydrocarbon bons maybe retained in thefinished product to give the desired volatility. Also in case there is a previous debutanization, such as inq the tower 20,1tmay be unnecessary to debutanize'again -in 5G the debutanizen. Sil. The debutanizer SI, accordf ingly, may be lay-passed by closing valve 91 inthe line 92 and valve. 93 in line; '5S and conducting the products through the lay-pass line |00 by opening valve iii. .165 In vthe fractionator 93 it is intended `to 'sepan rate the products of desired -boiling range, for example those' suitable for gasoline manufacture, 4s .nd pass them overhead through thevapor line |02.- The vapors are condensed in the condenser M3 and the condensate passed through the rundown line iM to an accumulator it A*Phe bottoms separated as aliquid .in the fractionator9d may be withdrawn .from the system through the line lill. All or a portion 'of these products .maym be'pas`sed Athroughthe line l0@ and pump-'H5' to the alkylation system. This heavy*-'productY -recycled to the allavlation system may beelkylvated in combination wi'h anyofthe materialsdescribed heretofore andintroduced from the lines, 3l, 5l and A51. It has been'found that" 'a portion of such heavy material may be'split and alkylated, thereby giving anfincreasedyieldb! 'v desired boiling range hydrocarbons.-

.Referring to iugmre 2. me c' drarnon'cnarge cated a pump il. rihis charge ordinarily comprises essentially a C@ cracked hydrocarbon fraction, such as a fraction from commercial cracking still gases. if the sulfur content of this gas is substantial, it maybe desirable to desulfurize the charge with aqueous caustic, such as B. caustic soda solution. Ordinary cracking' still gases can be handled without desulfurization, because this process avoids hydrogenation in which even small amounts of sulfur poison the hydrogenation catalyst. The charge is pumped through line l2@ and valve i22 to a preheater i124. The preheated product is passed through the line H wherein the hydrocarbons come in vcontact with recycle acid from line l2'i and new scid or make-up acid introduced through the line E29 in which is located a pump i3d. The acid may be about to 70% strength and preferably about 69% concentration. The temperature of the mixture is adjusted by heater lZ/.l and cooler' |32 in line E25 and may be around i60 to 180 F. The Vhydrocarbons are preferably maintained in the liquid phase'and suiicient pressure is maintained for this purpose. Ordinarily about to 200 pounds is suicient and preferably about pounds. A

The polymerization reaction is exothermic and on contacting the hydrocarbons with the acid there may be a temperature rise, for example 6 to f3" F., and in order to Vmaintain the temperature at the desired point, the products are passed through a cooler or heat exchanger E32 wherein the temperature is adjusted to the desired point, preferably about F. AThe mixture is then passed through the line i233 to polymerization vemels m5 and i236 which are connected in series by a connecting line |33. While two polymerization tanks are provided, it is to be understood that any number may be used and of suitable size to provide the necessary time for reaction. The time of reaction may vary from about 5 to 3G minutes and preferably about 20 minutes. The poiymerizatlon tanks are provided with baies, orifices or other suitable means for providing intimate Contact between the acid and the hydrocarbons. in the polymerization vessels it is intended that a selective polymerization take ltion of the reaction mixture may be recycled byA pump M6 in the system. It is preferable to main- 4tain suilicient recycle whereby the reaction mixture comprises about 1 volume of fresh charge, 4

volumes of recycled hydrocarbon and 5 volumes of recycled acid. It is preferable to maintain a. high proportion of recycled hydrocarbon in order to maintain a high ratio oi butenes to lsobutylene which is favorable for a large yield of the mixed polymer. The volume of recycled acid is maintained by allowing the materials in the settler |42 te stratify, whereby the acid may be withdrawn )irom the lower portion thereof and returned .through the line |50' to the line |21. The hydrocarbon reaction product is withdrawn from the .upper portion of the settler |42 through the line |02. The polymerization products may be treated in several dierent ways.

According to one method of operation, the hyunit through the lines aan 1,747

drocarbons, withdrawn from the separator |42 through the line |52, are passed through line Ell controlled by valve E55 to a mixer |56. In the mixer l5@ the acid oil is contacted with a neutralizing agent, such as caustic soda solutionA 300 F. to eect hydrolysis of any stable acid compounds. l

The hydrocarbon mixture separating in` the separator M53 is passed through line |63 in which may be located a heat exchanger or preheater (not shown) to a fractionator l'l'll wherein the butanes are distilled overhead through the vapor line ll| and conducted through condenser |72 and runl-down line 73 to an accumulator |15.

The dl-isobutylenes are collected on a chimney 2 'tray 'i776 from which they flow to a stripper |18. They are then withdrawn through the line Hill communicating with lines |52, |86 and |82 containing a suitable cooler (not shown) leading to an alkylation unit referred to hereinafter. Bottoms from the fractionator lill are withdrawn through the line |86. All or a portion of these bottoms may be lsent to the alkylation E85, |52, |86 and i132, suitable tankage (not shown) being provided. The product in the accumulator E15 usually contains a large proportion of isobutane and this, with or without further fractionation, may be passed through Iline |86 and line M32 to the alkylation system. This forced by pump i90 through lines I 86 and |82 to f alkylation tank lill connected in series by line 'i533 withl tank i192. These allrylation tanks are similar in construction to those referred to heretofore, in connection with Figure l, and provide means 4for intimately contacting hydrocarbons with an acid introduced through the valve controlled line |94 by pump |95. The acid is preferably sulfuric acid of about 94% concentration. In the alkylation tanks, it' is intended that alkylation of isobutane with the oleflns take place to form iso-octaneaas previously explained. In case there is insuiiicient isobutane to` bring the ratio of isobutane to olens up to the proper point, extraneous isobutane may be introduced into the system through the line |96 by pump |98. The reaction products are passed from the last allcyiation tank |92 through the line 200 to a separator 20| wherein the acid separates and is withdrawn through the' line 202, which communicates with the recycle line 204 containing a pump 205. All or a portion of the reaction productsvfrom the alkylation chambers may be recirculated by the valve controlled by-pass line 208. The spent acid may be withdrawn as desired through the valve controlled line 2|0.

latter product may contain a. suitable ratio of iso` aangaat The hydrocarbons separating in the separator '20| are conducted through the line 2| l, to a mixer 2|2 wherein they are contacted with a neutralizing agent, such as caustic soda solution, introvalve controlled line 2 I1 to a separator 2 I8 wherein the alkaline reagent is separated and withdrawn through the line 220 for recirculation or discharged from the system through the -valve controlled line 22|. The neutralized hydrocarbons are passed fromv the separator 2|8 through the line 222 to a debutanizer 225. from which excess butane or other undesirable low boiling products are removed overhead through the line 226, and these with or without fractionation may be recycled to the alkylation unit through suitable lines (not shown). The debutanized product is withdrawn from the lower portion of the debutanizer through vthe valve controlled yline 228 and passed to a fractionator 230 lwherein the motor fuel or gasoline fraction is fractionally, distilled andv passed overhead through thel vapor line 23|, condenser 232 and run-down line` 233 to an accumulator 235. The bottoms from the fractionator 230 may be withdrawn from'the system through the line 238 or may be recirculated' all orin part through the valve controlled line 240 to the alkylation operation, wherein it may be resubjected to alkylation, separately or in conjunction with other materials, referred to heretofore. This heavy product may besplit and alkylated into additional products boiling within the motor fuel boiling range.

According to another method of operation, the.A hydrocarbons from the separator |42 may be` passed directly to the alkylation operation through the lines |52, |86 and |82. In this way 'taken imA by the neutralization, hydrolysis and debutanizing operations maybe omitted.

As another modification, it is contemplated that the mixture of hydrocarbon and acid which may contain alkyl acid sulphates, may be passed all or in part from the last reaction vessel |36 throughl the branch line 242 controlled by valve 243 directly to the first alkylation tank |9| through lines |86 and |82. In such case, it is desirable to fortify the acid with a stronger acid to bring the strength of the mixture from Aabout the 69% strength up to alkylation strength, preferably about 94% strength. For this purpose strong acid, such as 98 or 100% sulfuric acid or even fuming acid of 105, 115 or 120% strength may be used. In this way the mixture of hydrocarbons and acid vfrom the .polymerization vesselsE |35 and E36 may be subjected directly to alkylation in the presence of isobutane, extraneously added if necessary.

` According to still another method of operation,

the spent'acid withdrawn from the alkylation unit may be recycled'in whole or part to the polymerization unit. As shown in Figure 2 the acid withdrawn from separator 20| may be passed by pump 250 through line 2|0 and a suitable cooler| to a lsettler 252, vwhere stratification l' is allowed to take place. The acid discharged from the alkylation 'unit generally has aconcentration of about 80 to 90% 'or somewhat higher, the balance being mainly organic material the acid. While this acid would require reviviilcation or-fortiilcation for reuse in the alkylation t, economy maybe eiected by this acid with waterto reduce it to the required concentration for the polymerization reaction, and then usingth'e diluted acid as a part ofthe acid 'charge the polymerimtion reaction. As shown, water for dilutionpurposes is introduced into the acidthrough line 253 containing pump 254 in advance of the cooler 25|, so that this cooler absorbs the heat of dilution. The cooled and diluted acid will then stratify inv settler 252 into a lower acid'layer and an upper oily' sludge layer, the latter being removed from the settler by line 255. Thel diluted acid. layer ijs then forced by pump 256 through line 251 to the acid feed line |29 of the polymerizaev tion unit. j It is to be understood scribed here'inbefore, as applied to a combination polymerization andallavlation operation, are useful in a separate alkylation process. ample, the recycling of the materials withdrawn from the alkylation tanks either before or after separation of the acid and hydrocarbons (including the acid-hydrocarbon emulsion and the separated acid, or both) and the recycling of certain heavier fractions of the product obtained in the For ,i exthat certain features defractionation of the alkylate to separate the desiredmotor fuel-hydrocarbons therefrom, may

' be employed in any type of alkylation operation.

' presence of a solid Example I A C4 fraction comprising' about 16% isobutylene, 23% of normal butylenes, 18% isobutane and 43% n-butane, was subjected to polymerization in the phosphoric acid catalyst, consisting of a calcined mixture of phosphoric acid and kieselguhr. A pressure of about 550pounds and temperature of about 320 F. was maintained on the reaction mixture. The resulting'product comprised about 22% iso-octenes, 4% 'polymer bottoms and about 74% residual C4s. The residual gases comprised about'21/% isobutylene,

61/2 normal butylene and 9,1% butanes The product was debutanized and the debutanized product subjected to fractionation to separate the iso-octenes. The iso-octenes werethen sub-- jected' to an alkylation operation in the presence of isobutane and sulfuric acid of about 94% concentration at a temperature of about 90 F. The ratio of isobutane to olefins in the feed was about 3:1. A gasolene fraction containing a large proportion of iso-octanes and having an antiknock 170 F., under a pressure of about 150 value of about 90 was obtained. The yield was about 165% based on the iso-octenes.

Example II A Cr fraction comprising about 18% isobutyiene, 28% of normal butylenes and about 22% iso and 32% normal butanes, was subjected to polymerization in the presence of sulfuric acid of about`69% strength, at a temperature of about pounds forl a period oi approximately 20 minutes. A portion -of the. reaction products was recycled to mainf tain a recycle ratio of total hydrocarbons to fresh C4' hydrocarbon charge of about 7:1 and a recycle ratioV of total hydrocarbons to isobutylene of about :1. The ratio of acid to. totalhydrocarbons was about 1:1 by. volume. "I'he reaction products were passed to a separator in which the acidy was separated and recycled tothe system and the hydrocarbons were neutralized with dilute caustic soda to remove acidity. The result- 'ing product vcontained about 20% of iso-octencs, about 4% heavy polymer bottoms, and approximately 76% of residual gases. The product was.

fractionated to separate the iso-octenes which were then subjected to an alkylation operation in the presence of isobutane a.nd su1iuric a'cidj75A of about 94% strength under a pressure of about 50 pounds and a temperature of about 90 'i5- for a period of about an hour. A. yield of normally iiquid hydrocarbons falling within the gasoline boiling point range ofl about 165% based on the iso-octenes was obtained, having an antiimocls value of about 90.

Example 1H The residual gases from the hot acid polymerization process of Example H contained about l21/% of normal butylenes and about EWI/2% bue tenes. The proportion of isobutane in the bu tenes was about 36%. The residual gases were subjected to an alkylation operation in the presence of sulfuric acid of about 94% strength under pressure of about 50 pounds and temperature of about 90 E'. for a period of about one hour. A gasoline product, amounting to about 150% based on the olens consumed and having an antilrnock value of about 90 was obtained.

Ezample IV The product from the hot sulfuric acid poly merization step of Example U, comprising acid and hydrocarbons, was subjected directly to an alkylation operation in which sulcient strong acid of about 100% was added to bring the acidity up to about 93%. Sufficient extraneous isobu= tane was added to bring the `ratio'of isobutane to 'oleiins to about 3:1. The mixture under a pressure of about 50 pounds and a temperature of about il" F., was allowed to react for about an hour. The total reaction products, including hydrocarbons, were recycled in sumcient amount to maire the reaction mixture about l part of fresh feed, about e parts of recycle hydrocarbons and about parts of acid. The reaction products were separated, the acid recycled to the system and having an antilmock value of about 90.'

Obviously many vmodifications andvariations of the invention, as hereinbefore set forth, may

.be made without departing from the spirit and scope thereof, and therefore only such limitations should be imposed as are indicated in the appended claims.

We claim 1. A process for the alkylation of hydrocarbons, which comprises maintaining a circulating stream of reaction mixture comprising strongsulfuric acid and hydrocarbons in a closed circuit, .introducing into said stream olens and low boiling isoparaiflns in such amounts that an excess of isoparains is maintained in the mixture, withdrawing reaction products fromv said stream and separating from the products Withdrawn the alkylated hydrocarbons.

2. A process for the manufacture of high antiknock gasoline hydrocarbons which comprises subjecting an unsaturated Ct hydrocarbon fraction containing iso and normal butylenes to partial polymerization in the presence of a polymerization catalyst under selective polymerization conditions whereby di-isobutylene polymers are produced, separating said polymersfrom the residual gases, contacting said residual gases in a reaction zone maintained under alkylating conditions with strong sulfuric acid and with isobutane in an amount in excess of the olenns, .whereby the iaobutane is alkylated by the oleflns,

withdrawing acid and hydrocarbon reaction products from said reaction zone, recycling a substan- @grt 11,74%

tial proportion of said acid and hydrocarbon ren action products to the reaction zone to maintain therein a materially/higher ratio of acid and isoparamns to olefins than normally present in the fresh feedsv of oleiins, isoparalns and acid to said zone, and separating the allryiation products from the unrecycled portion of the reaction products.

3. A process for the manufacture of normally .liquid hydrocarbons of high antiknoclr value from an unsaturated C4 hydrocarbon fraction containing isobutylene, normal butylencs vand isobutane, which comprises treating the hydrocarbons with sulfuric acid of about 60 to '70% concentration to remove the isobutylene, subjecting the re,- maining hydrocarbons in the presence of an eX- cess of lsobutane to the action of sulfuric acid of about 92 to 98% concentration in a reaction zone to allrylate the isobutane with the normal butyienes, withdrawing acid and hydrocarbon reaction products from said zone, recycling one portion of said acid and hydrocarbon reaction products to the reaction zone in sufficient amount to maintain therein a substantially higher ratio of acid and isoparaffin to olens than in the fresh feeds of'acid and hydrocarbons to said zone, separating the"hydrocarbons from the other portion of the reaction products, fractionating the hydrocarbons to obtain a fraction rich in isobutane and recycling said fraction to the reaction zone to increase the ratio of isobutane to 'olens therein.

A process for the alkylation of hydrocarbons, which comprises continuously feeding olens, an excess of low boiling isoparainns and strong sulfuric acid to a reaction zone maintained under alhylating conditions whereby the isoparafllns are alkylated by the oleflns, withdrawing acid and hydrocarbon reaction products from said zone, recycling one portion of said withdrawn acid and hydrocarbon reaction products to the reaction zone to maintain therein a substantially higher ratio of acid and isoparains to olefins than normally present in the fresh feeds of olens, isoparamns and'acid to said zone, separating a liquid hydrocarbon fraction from the other portion of said withdrawn reaction products and recycling at least a portion ofrsaid fraction to the reaction zone.

5. A process for the alkylation of hydrocarbons, which comprises continuously feeding olefins, an excess of low boiling isoparafns and strong sulfuric acid to a reaction zone maintained under alkylating conditions, whereby the isoparaiflns are alkylated by the oleilns, withdrawing acid and hydrocarbon reaction products from said zone, recycling one portion of said Withdrawn acid and hydrocarbon reaction products to the reaction zone to maintain therein a substantially higher ratio of acid and isoparaffins to oleflns than normally present in. the fresh feeds of olens, isoparafns and acid to said zone, separating the hydrocarbons from the other portion of said withdrawn reaction products, fractionating said hydrocarbons to obtain a lighter fraction zone maintained under alkylating. conditions,

vproportion of thev withdrawn acid and hydrocarbon reaction products to maintain in the reaction zone a materially higher ratio of acid and iso- `paraiilns to oleiins than normally present in the fresh feeds of olens', isoparains and acid thereto, and separating the alkylated products from the remaining portion of the reaction products.

'1. A process for the alkylation of hydrocarbons,

.which ycomprises continuously subjecting olefincontaining hydrocarbons and an excess of low boiling isoparalns to the action of strong sulfuric acid in a reaction zone maintained under alkylating conditions, withdrawing acid and hydrocarbon reaction products from the reaction zone, recycling one portion of the withdrawn acid and hydrocarbon reaction products to said zone to maintain therein a substantially higher ratio of isoparafilns to oleflns than normally present in the fresh feed of oleilns and isoparafflns thereto,

separating the acid and hydrocarbons from the other portion of the reaction products, recycling at least a portion of the separated acid to the reaction zone and recovering from the separated hydrocarbons the alkylated hydrocarbons.

V8. A process according to claim 7, in which at least a portion of the separated acid-is withdrawn from the system and fresh acid added in sufilcient amount to make up for the portion withdrawn.

v9. A process for the alkylation of hydrocarbons, which comprises continuously feeding oleflns, an

^ excess of low boiling' isoparafiins and strong sulfurie acid to a reaction'l zone maintained under alkylating conditions whereby the isoparaiilns are alkylated by the oleiins, withdrawing acid and hydrocarbon reaction products from said zone,

' recycling one portion of said withdrawn acid and v hydrocarbon reaction products Ato 'the reaction zone to maintain therein a substantially higher ratio of acid and isoparailins to oleilns than normally present in the fresh feeds of olens, isoparains and acid to said zone, separating the hydrocarbons from the other portion of said withdrawn reaction products. fractionating said hydrocarbons to obtain a fractionv rich in the excess isoparaiiins and recycling said fraction to the reaction zone.

10. A process for the alkylation of lhydrocarbons, which comprises circulating a stream containing low boiling'isoparafilns and strong sulfuric acid through a circuit comprising an enlarged reaction zone, introducing hydrocarbons containing oleiins andisoparailins into said stream, theY proportions`of said olens and isoparafns being such that an excess of isoparafilns over oleflns is continuously maintained therein,

intimately contacting the oleflns and isoparafilns with the acid in said reaction zone under alkylat- 4knock gasoline hydrocarbons ing conditions whereby the isoparafnns are alkylatedl by the olens, withdrawing reaction prodproducts. ll.. A process according to claim l0, in which the hydrocarbons introduced into said stream are a residual C4! fraction of cracked hydrocarbon gases from which di-isobutylene polymers have been recovered by selective catalytic polymerization.

12. The method according to claim 2 in which polymers produced-in the polymerization stage are passed to the alkylation zone for alkylation with the isoparaflln.

13. A process for the manufacture of high anti- -which comprises subjecting a normally gaseous lwdrocarbon fraction containing C3 and' C4 olens including isoand normal butylenes to partial polymerization in the presence of a polymerization catalyst under polymerization conditions and whereby polymers are produced, separating said polymers from the i residual gases, contacting said residual gases in a reaction zone maintained under alkylating conditions with strong sulfuric acid and with an isoparaflin vfraction comprising isobutane in an amount in excess of the olens, whereby the isoparaihns are alkylated by the oleiins, withdrawing acid and hydrocarbon reaction products from said reaction zone, recycling a substantial proportion of said acid and hydrocarbon reaction products to the reaction zone to maintain therein a materially higher ratio of acid and isoparailins to olens than normally present in the fresh feeds of olefins, isoparailins and acid to said-zone, and separating the alkylation products from the unrecycled portion of the reaction products.

14. The method according to claim 13 in which polymers produced in the polymerization stage are passed to the alkylation zone for alkylation with the isoparafiins. Y

15, A process for thexalkylation of hydrocarbons which comprises.. maintaining a circulating stream of lreaction mixture comprising strong sulfuric acid and hydrocarbons in a closed circuit, introducing into said stream olefins and low boiling isoparains of isoparafilns is maintained in the mixture, withl' drawing reaction products from said stream, separating from the products withdrawn the alkylated at least a portion ofy said heavier fraction to said ARTHUR n. Gomsny.' CLAUDE w. wA'rsoN.

closed circuit.

in suchamounts that an excess 

